The present invention relates to a motor vehicle including an automatic transmission and an engine with an exhaust brake system, and more particularly to a control of such an exhaust brake system.
A known automatic transmission has a manual selector lever having a D range and a 2 range. When the 2 range is selected by the manual selector lever, the automatic transmission is conditioned in engine brake running state where a direct motion connection is established between the transmission input and output shafts. If, under this condition, an exhaust brake switch is turned on, an exhaust brake system becomes in operation to cause activation of exhaust brake. With the automatic transmission in the engine brake running state and the exhaust brake activated, if the vehicle speed drops down to a vehicle speed value at which the automatic transmission effects a downshift, a great shift shock cannot be avoided. The present invention aims at alleviating this problem.